investigation on the deinkability of old newspaper

in this study, deinkability of old newspaper by conventional method and the effect of washing, flotation and combined washing/flotation processes were investigated on optical and superficial properties of the produced papers. the results from measuring of the optical and superficial properties indicated that using chemical treatment time of 20 minute and one stage washing resulted the papers with the highest brightness degree of 50.9% iso and the lowest yellowness degree of 14.8% iso, opacity degree of 97.8% iso, dirt count of 507 and dirt area of 2205.5 mm2/m2. when the flotation process applied solely to deinking, opacity degree was improved to 99% iso while the papers produced had lower brightness and higher yellowness, dirt count and dirt area. also, the results obtained from distribution and the area of ink particles on both wire and felt sides of the papers showed that wire side of papers contained the higher ink count and ink area. with regard to the results obtained from optical and superficial properties of the made papers from deinking of old newspaper, application of washing process has more efficiency for removing of ink particles compared to flotation or combined washing and flotation processes, and the made papers have more desirable optical and superficial properties.